Switching bevice



H. G. MACDONALD.

SWITCHING DEVICE.

APPLlcATmN FILED JULY 11.1916.

,QSOp Patented ct. 28, 1919.

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ga-Dj@ ATTORNEY UNITED sTATEs PATENT oEEioE.

HOWARD G. MACDONALD, OF MURRAYSVILLE, PENNSYLVANIA, ASSIGNOR TO WEST- IN GHOUSE ELECTRIC AND MANU FACTUIEtINC--v COMPANY, A CORPORATION 0F' PENNSYLVANIA.

SWITCHING DEVICE.

To all whom t may concern.'

Be it known that I, HOWARD G. MAoDoN- ALD, a citizen of the United States, and a resident of Murraysville, in the county o1 Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Switching Devices, of which the Jfollowing is a specification.

My invention relates to switching devices and systems and particularly to means for controlling 'the starting of large-capacity electric motors and other similar devices by the use of circuit interrupters.

The object of my invention is to provide devices of the above indicated character that shall have means for so interlocking the various switches or circuit interrupters that one of the starting switches cannot be opened until the running switch has been closed.

In the carrying out of my invention, I provide starting ,switches that are adapted to be closed simultaneously for the purpose of supplying the motor with current at a relatively low voltage through an autotransformer. One of the switches is adapted to be latched in its closed position when the other switches are opened, for the purpose of supplying the motor with current at an intermediate voltage through the autotransformer. A running switch is provided for connecting the motor directly to the main circuit, and means is also provided for tripping the starting switch that is latched in its closed position after the running switch is closed. A

Figure 1 of the accompanying drawings is a diagrammatic view of circuit interrupters or switches embodying my invention, and Fig. 2 is a diagrammatic view of a system embodying my invention.

A motor 1 is supplied with energy from a circuit 2 and is adapted to be started, through an auto-transformer 3, by the manipulation of starting switches 4 and 5 and a running switch 6. The three conductors of the circuit 2 are connected, through a main switch 7 to three conductors 8, 9 and 10. The conductors 8, 9 and 10 are connected to the stationary contact members 11 and 12 of the switches 4 and 6, respectively. The stationary contact members 13 of the switch 6 are connected to the motor 1 and to intermediate points 14 in the windings of the auto-transformer 3. The stationary Specification of Letters Patent.

Application filed July 11, 1916.

Patented Oct. 28', 1919.

Serial No. 108,577.

contact members 15 of the switch 4 are connected to the terminals 16 of the auto-transformer 3, and the terminals 17 of the auto,- transformer?) are connected to the stationary contact members 18 of the switch 5. The stationary contact members 19 of the switch 5 are connected together by a conductor v20. The switch 6 is provided with an auxiliary movable` contact member 21 that is adapted to engage auxiliary stationary contact members 22 for the purpose of completing a circuit comprising the trip coil 23 of the switch 4 and the 4secondary winding of a potential transformer 24 the primary winding of which. is operatively connected to two conductors of the circuit 2. The switch 6 is provided with trip coils 25 that are operatively connected to series transformers 26 for the purpose of tripping the switch 6 under pre-determined circuit conditions.

In Fig. l of the drawings, the switch 5 is shown as comprising a lever arm 27 for .supporting its movable contact membersV and a toggle mechanism 28 that is operatively connected, through a series ofrods 29 and bellcrank levers 30, to an operating handle 31. The toggle mechanism 28 is also operatively connected, through a rod 32, to the freely movable lever arm` 34 of the switch 4. The lever arm 34 is provided with a latch 35 that is adapted to engage an operating toggle mechanism 36. The switch 4 is provided also with a lever arm 37 that is adapted to support its movable contact members and to be actuated by the operation of the toggle mechanism 36. A latch 38 is provided 'for holding the toggle mechanism 36 in its set or closed position, and the tripping device 23 is adapted to actuate the latch 38 to trip the switch 4, under predetermined conditions. The switch 6 is similar to the switch 4 with the exception that it is provided with an auxiliary movable contact member 21 `that is adapted to engage auxiliary stationary contact members 22 when it is closed, for the purpose of supplying the tripping device 23 with energy from the circuit 2, substantially as hereinbefore set forth.

When it is desired to start the motor 1, the operating handle 31 is moved to the position shown in Fig. 1 of the drawings to thereby close the starting switches 4 and 5. This will cause the motor 1 to be supplied with current, through the transformer 3, at

a relatively low voltage that is just suiiicient to cause it to accelerate. next moved to such position that the switch 5 is opened, but, when it is so moved, the latch 3S is adapted to hold the toggle mechanism 36 of the switch 4 in such position that the switch 4 remains in its closed posi tion. Thus. the motor 1 will be supplied with current, through the transformer 3, at an intermediate voltage. Vhen the motor 1 has reached its maximum acceleration at the intermediate voltage, it is advisable to connect it directly to the circuit 2, and, for this purpose, the switch 6 is provided which, when it is closed, causes its auxiliary movable contact member 21 to so engage the auxiliary stationary contact members 22 as to energize the tripping device 213. When the tripping device 23 is energized, the latch 18 is moved to such position as to permit the toggle mechanism 36 of the switch 4 to buckle and the switch 4 to be opened.

By the use of my invention, standard circuit interrupters or switches may be utilized for starting high-capacity motors or other similar devices, and the likelihood of opening the starting switches before the running switch is closed is precluded.

My invention is not limited to the particular structures illustra-ted, as many modiications may be made therein without departing from the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention:

1. A switching system comprising two switches adapted to be closed simultane ously, means for latching one oi the said switches in its closed position when the other is opened, a third switch, and means dependent upon the closing oil the third switch for causing the said latched switch to open.

2. A switching system comprising two switches, means for so mechanically connecting` the switches as to cause them to be closed simultaneously, means for latching one ot the said switches in its closed position when the other switch is opened, a third switch, and means controlled by the closing oi the said third switch for unlatching the switch that is latched in its closed position.

3. A switching system comprising two switches, means for so mechanically connecting the switches as to cause them to be closed simultaneously, means for latching The handle 31 is one of the said switches in its closed position when the other switch is opened, a third switch and electrical means controlled by the closing of the said third switch for permitting the opening` of the switch that is latched in its closed position.

4. A switching system comprising two mechanically connected switches, a lost-motion means for permitting the opening of one switch while the other remains closed, a third switch, and means actuated by the third switch for causing the closed switch to open when the said third switch is closed.

5. In a motoikstarting system, the combination with two starting switches, ol means for simultaneously closing the starting switches and for permitting the nonautomatic opening of only one of the starting switches, a running switch, and means for automatically opening the other starting switch after the running switch is closed.

6. In a motor-control system, the combination with two starting switches, oll means for causing the switches to be closed simultaneously, lost-motion means for permitting the opening' ot only one switch, a running switch, and means tor causing the automatic opening of the other starting switch atter the running switch is closed.

7. l'n an electric circuit, the combination with a motor, and an auto-transiiormer, ot two starting switches adapted to be closed simultaneously to connect the .motor vto relatively low-potential points on the autotransiormer, means for latching one ot the switches closed when the other is opened to connect the motor to points of intermediate potential on thel auto-transformer, a third switch for connecting the motor directly 'to the electric circuit, and means controlled by the operation of the third. switch for causing the opening ot the latched starting switch.

8. In a motor-control system, the combination with a starting` switch and a running switch, ot means for latching the starting switch closed, and means for eileeting the automatic opening of the starting switch after the ruiming switch is closed.

In testimony whereof, I have hereunto subscribed my name this 29th day of June 1916.

HOWARD Gr. MACDONALD.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

